It has been demanded that a microregion on the nanoscale or microscale be observed using an electron microscope. As an observation method or a measurement method therefor, there are an observation method in which observation is made while applying a voltage to a microregion of a sample, a measurement method in which an absorbed electron current of a microregion is measured using an electron microscope, an observation method in which observation is made using an electron microscope in a state where a microregion is grounded, and the like.
In the case where observation or measurement as described above is made, local wiring is sometimes performed in a microregion so that local voltage application or local ground connection can be made.
As a method of performing local wiring, there is a gas deposition method using a focused ion beam as disclosed in PTL 4.
Further, PTL1 discloses a method of forming a conductive pattern by inkjet printing using an ink containing conductive particles and an ionic liquid. The ionic liquid has a characteristic that a liquid state is maintained even under vacuum conditions.
PTL 2 discloses a method of observing a biological sample in its original form by impregnating or applying an ionic liquid into or onto a water-containing sample so as to prevent the evaporation of water under vacuum conditions.
Further, PTL 3 discloses an observation method in which an ionic liquid is held in a sample holding member having an opening, and a sample is floated in the ionic liquid and observed.